Abstract

Salinity is one of major environmental constraints that adversely affect plant growth and pose a serious threat to crop productivity. One basic concern is related to tissue sensitivity differences to salt stress. It is intriguing that much more research efforts have been directed to shoots/leaves than roots, although roots are the first tissues directly encountering salt stress and acting as its sensor. We focused on the tissue sensitivity differences to salt stress in wheat seedlings by adopting a novel tip bioassay. The tip bioassay employed a set of 5-mL pipette tips filled with vermiculite placed over racks containing NaCl solution. Using this simple device, after determining the time course of growth inhibition under varying concentrations of NaCl, we compared the salt sensitivity in 19 diverse germplasms from five Triticum species after 7 and 14 days of exposure to 200 mmol/L NaCl. Markedly greater reduction in root length than shoot length was observed in all lines. Both the magnitude and relative rate of inhibition were much greater in roots than shoots and significant differences were observed in tissue, line, stress duration and their interactions. Our tip bioassay demonstrated that roots were more sensitive than shoots to the growth-suppressing effect of salt during the early seedling stage in wheat. These results point out the need of further research targeted on the role of and communication between roots and shoots in salt stress sensing and response.

摘要

盐分是对植物生长造成不利影响并严重威胁作物生产力的主要环境限制之一。一个基本问题与组织对盐胁迫的敏感性差异有关。有趣的是，与根相比，针对芽/叶的研究工作更多，尽管根是直接遇到盐胁迫并充当其传感器的第一批组织。我们通过采用新型尖端生物测定法，重点研究了小麦幼苗对盐胁迫的组织敏感性差异。针尖生物测定法使用一组5 mL移液器针尖，填充了ver石，放置在装有NaCl溶液的架子上。使用这个简单的装置，在确定了不同浓度的NaCl的生长抑制的时间过程之后，我们比较了来自五个物种的19种不同种质的盐敏感性暴露于200 mmol / L NaCl的7和14天后的普通小麦种。在所有品系中均观察到根长的减少明显大于芽长。根部的抑制幅度和相对抑制率都比芽大得多，并且在组织，品系，胁迫持续时间及其相互作用方面观察到显着差异。我们的尖端生物测定结果表明，在小麦苗期早期，根部对于盐分的生长抑制作用比芽更敏感。这些结果指出有必要针对盐胁迫感测和响应中根与芽的作用和通讯进行进一步研究。